She's Running pretty good , lots of mid and top end power but it is being a little goofy at idle. When I give it a quick rev , like 3 quarter throttle and let off it doesn't come back to idle right away it sits there and babbles, slowly works it's way down to an idle with the revs going up and down .any suggestions on what might be wrong ?

 

1) Pressure test the motor to be sure you do not have a vacuum leak (damaging). This leak would most likely be in the intake boot or main bearing seals. Go to Duncan Racing's web site for a description of this procedure and how to make your own tester (very easy). If the pressure test shows that you have no leak then proceed to #2.

2) Your throttle slide could actually be too low. I experienced this problem with my LT500. The throttle slide had worn down in the area the idle screw contacts it. Thus the idle screw could no longer raise the slide enough and the engine ran very erratic at idle. It would rev up and down and often at an rpm much higher than normal. These are some of the same symptoms experienced with an air leak.

 

I'll agree Triple,

An air leak definately comes to mind. (Air leak = lean)

Ballz,
If you've been tinkering with the jetting, or done any mods that would require a change, it could also be a grossly lean condition.
I've seen this happen before also.

Richen the pilot and needle for starters...

Just a thought

 

I'm running a # 460 main jet right now with my needle @ 2nd notch from the bottom and the plug is a light brown , 35:1 gas mix and a BR8 plug. when I my needle at the middle notch or any higher it was a real pain to start and was flooding itself out. It is not running near as crisp as it should be. I'm off tomorrow so I am going to check out my reed cage and the condition of the rubber, hopefully it is an easy fix and not my crank seals because I just put brand new ones in. thanks for your input guys.

 

I haven't had much luck running Resistor plugs either... Just my opinion. I'd stick to a B8ES

Another trick you could try would be find some flammable carb cleaner and spray around base gasket, intake boot, reed gaskets... anywhere you have a mating surface (With the motor running) and see if you get an increase in rpm. Sometimes you can find a leak that way.

You might need to do some studying on carb tuning... the main jet size only comes into play around full throttle.
(Still need to look at the size of the pilot jet)
Moving the needle one click shouldn't make it unreasonably rich. I'm wondering if you shouldn't totally dismantle the carb, and make sure it's clean...(Using carb cleaner and compressed air in all the passages) sounds like there's something else going on here.

 

Hey guys I took the carb apart yesterday and cleaned it up with some carb cleaner and my blow gun, it was really clean no obvious deposits of any kind. I checked out my pilot jet and it is the stock one which is a # 30. Do you think I should go to a larger one ? my seal between my carb and cylinder head seems to be really good. It idles really nice, it's just when you let off the gas at full or 3 quarter throttle that it seems to take forever to come back to an idle again. Does a # 460 main jet seem too big for what I've done to my engine ? other people seem to think so.

 

Jetting is so dependant upon air density and mods that just picking a jet number is nearly impossible.

The pilot sounds a little small to me, and the main sounds a little big... but no two bikes are the same.

I wouldn't mess with the main just yet, and try going to a 35 on the pilot... see what happens. It SHOULD help... but if you are having other problems the change probably won't do much.